However, the PC that you plug the flashdrive into needs to have truecrypt installed on it. Truecrypt basically encrypts a virtual drive on the same size as the physical drive and then the software mounts that virtual drive once you supply the correct password. When opening files on the encrypted flashdrive, the data is decrypted in real time through the random access memory. The password also stays in the RAM, so it's very difficult to crack.
Try out Kakasoft USB Security. It works well on windows. Since you cannot install apps on your work machine, install the app to your flash drive. moreover is a freeware.http://www.kakasoft.com/usb-security/